The present invention relates generally to radiation dose-rate monitors and more specifically to a wide-range dose-rate monitor which does not require scale switching for wide-range radiation dose-rate monitoring. This invention is a result of a contract with the United States Department of Energy.
Most radiation monitors, like the personal pocket dosimeter for example, measure the degree of discharge of a capacitance-type device which is discharged by the current from an ionization chamber. Such a measurement is equivalent to the total absorbed radiation dose. For a person suddenly exposed to radiation field, a measurement of the dose-rate would be more useful than the total dose.
The Federal Emergency Management Agency (FEMA) has requested that a wide-range radiation dose-rate monitor be developed. The new instrument should span the range of two existing dose-rate meters, the CDV-700 and the CDV-715, because in an emergency radiation situation a person should not have to perform scale switching operations to obtain a dose-rate reading.
In particular, an instrument is needed which has the following characteristics:
(1) sensitivity in the range from 0 to 500 Roentgens/hour (R/h), readable on one nonswitchable scale; PA0 (2) linear readout in the range from 0 to 0.5 R/h; PA0 (3) nonparalyzable and nonsaturatable response to radiation; PA0 (4) small size, portability, and low power consumption.